Seed disinfection treatments do not sufficiently eliminate the infectivity of Cucumber green mottle mosaic virus (CGMMV) on cucurbit seeds

Abstract

Tobamoviruses induce crop diseases that are responsible for significant economic losses around the world. Like other tobamoviruses, Cucumber green mottle mosaic virus (CGMMV) forms highly stable particles that can persist for long periods on plant debris, in soil and on seed surfaces. These particles serve as a primary source of infection, infecting seedlings from which the virus can then be mechanically transmitted to other neighbouring plants. Contaminated seeds also provide a route for the movement of the virus between countries and its introduction into new areas. Effective seed disinfection treatments and the use of uncontaminated seed may reduce the global prevalence of this virus. Several treatments based on the use of heat or chemicals have been reported to effectively eliminate CGMMV and other tobamoviruses from seeds. An evaluation of these treatments on highly contaminated seed lots revealed inconsistent results, which encouraged the construction of a more accurate detection method that combines morphological, serological, molecular and biological analyses in one protocol. The detection of viable (infectious) viral particles in seed treated with heat, trisodium phosphate or a combined treatment, indicates that these treatments are insufficient. The serological detection of CGMMV in the inner parts of infected seeds provides a possible explanation for the inconsistent efficacy of these treatments.